Disclosed examples generally include methods and apparatuses related to microphone units, such as may be found in implantable medical devices (e.g., cochlear implants). Microphone units generally include a microphone element connected to a chamber having a concave floor with the chamber covered by a membrane. Microphone units can be configured to produce an output based on pressure waves (e.g., sound waves) that reach the membrane. In an example, a microphone unit has a pressurized gas within the chamber below the membrane such that, while in a static state, the membrane deflects away from the chamber floor.

The present disclosure provides a microphone including at least one acoustoelectric transducer and an acoustic structure. The acoustoelectric transducer is configured to convert a sound signal to an electrical signal. The acoustic structure includes a sound guiding tube and an acoustic cavity. The acoustic cavity is in acoustic communication with the acoustoelectric transducer, and is in acoustic communication with outside of the microphone through the sound guiding tube. The acoustic structure has a first resonance frequency, the acoustoelectric transducer has a second resonance frequency, and an absolute value of a difference between the first resonance frequency and the second resonance frequency is not less than 100 Hz. By disposing different acoustic structures, resonance peaks in different frequency ranges may be added to the microphone, which improves a sensitivity of the microphone near multiple resonance peaks, thereby improving a sensitivity of the microphone in the entire wide frequency band.

In an embodiment, a system for detection of trains at railroad crossings is provided. The system comprises a field-deployed detection and reporting device comprising a microphone, a communication module, a microprocessor, and an application. When executed on the microprocessor, the application receives data describing sounds captured by the microphone and identifies frequencies of a first received sound. The application also transmits, based on the identified frequencies and a formula, a first message via the communication module. The first received sound is generated by a warning bell sounded at the railroad crossing. The first message is received by a backend server that issues a first broadcast based on receipt of the first message. The application further determines that the first received sound discontinues. Based on the determination, the application sends a second message via the module to the backend server which issues a second broadcast that the crossing is reopened.

The embodiments of the present disclosure may disclose a vibration sensor, including: an acoustic transducer and a vibration assembly connected with the acoustic transducer. The vibration assembly may be configured to transmit an external vibration signal to the acoustic transducer to generate an electric signal, the vibration assembly includes one or more groups of vibration diaphragms and mass blocks, and the mass blocks may be physically connected with the vibration diaphragms. The vibration assembly may be configured to make a sensitivity degree of the vibration sensor greater than a sensitivity degree of the acoustic transducer in one or more target frequency bands.

A voice reception device includes a casing and at least two voice reception units. The casing includes a peripheral side wall, a bottom wall, a containing space formed in an inside of the peripheral side wall and the bottom wall, and a first opening end located at an end of the containing space. The voice reception units are disposed in the containing space. Each of the voice reception units includes a main body, a diaphragm, and a voice guiding channel. The main body has a chamber, and an end of the chamber has a second opening end. The diaphragm is connected to the second opening end of the main body. The voice guiding channel includes an importing end acoustically connected to the chamber and an exporting end opposite to the importing end and acoustically connected to a microphone.

According to certain embodiments, a microphone array having a plurality of microphone elements is calibrated by ensonifying the microphone array at a first direction relative to the microphone array with a first acoustic signal to concurrently generate a first set of audio signals from two or more of the microphone elements and processing the first set of audio signals to calibrate the two or more microphone elements. One or more other sets of audio signals can be generated by ensonifying the microphone array with one or more other acoustic signals at one or more other directions relative to the microphone array, where the two or more microphone elements are calibrated using the first set and the one or more other sets of audio signals. The calibration process can be performed outside of an anechoic chamber using one or more acoustic sources located outside or inside the microphone array.

In an exemplary embodiment, a system is provided that includes a sensor, a computer memory, and a processor. The sensor is configured to be disposed on a vehicle, and is configured to obtain sound or vibration data for the vehicle. The computer memory is configured to store a plurality of known signatures pertaining to a plurality of different types of vehicle theft events. The processor is configured to: compare a signature of the data with the plurality of known signatures stored in the computer memory; and determine whether a vehicle theft event is occurring based on the comparing of the signature of the data with the plurality of known signatures.

Dipole audio speakers, and more particularly, voice controlled dipole audio speakers having at least one microphone located substantially along the null sound plane of the dipole audio speaker. An improved loudspeaker system that produces an improved audio quality for stereophonic sound. The improved loudspeaker utilizes conventional electro-dynamic drivers in a sealed chamber that produce sound primarily in the 20-300 Hz band coupled with electrostatic card stack drivers placed outside the sealed chamber that cover the remaining 98% of the audio frequency spectrum (300 Hz to 20 kHz). The improved loudspeaker system can also include multiple card stack drivers that are placed at angles with respect to each other to maximize audio fidelity.

Methods and devices provide physiological movement detection with active sound generation. In some versions, a processor may detect breathing and/or gross body motion. The processor may control producing, via a speaker coupled to the processor, a sound signal in a user's vicinity. The processor may control sensing, via a microphone coupled to the processor, a reflected sound signal. This reflected sound signal is a reflection of the sound signal from the user. The processor may process the reflected sound, such as by a demodulation technique. The processor may detect breathing from the processed reflected sound signal. The sound signal may be produced as a series of tone pairs in a frame of slots or as a phase-continuous repeated waveform having changing frequencies (e.g., triangular or ramp sawtooth). Evaluation of detected movement information may determine sleep states or scoring, fatigue indications, subject recognition, chronic disease monitoring/prediction, and other output parameters.

A MEMS device includes a package for providing an inner volume, a MEMS microphone arranged in the inner volume, a sound port through the package to the inner volume, and a passive acoustic attenuation filter acoustically coupled to the sound port.